This was every year the official start for the Carnival of Venice.
By law everybody was allowed to wear a mask, and so the population of Venice in mass, well dressed, the face well hidden by an elegant mask, took the traditional showoff walk in Campo Santo Stefano.
"Liston" means in Venitian dialect "path", "stripe". It is a way of describing that strip of the city where everybody was, the cool world go. The traditional Liston later moved toward San Marco square, due to space reasons (Campo Santo Stefano is relatively small).
This was the special day when everybody was showing off all their richness, silk, gold and precious stones. And after the walk (back and forth downtown) the hype was going to a special restaurant, or to the Theater.
There is a modern Italian expression for this kind of appearing. It is "fare le vasche" (swim in the pool).
It gives the idea of going back and forth, exactly like in a swimming pool …